Kaganowicz in a copending application entitled, "METHOD FOR PREPARING AN ABRASIVE COATING", Ser. No. 963,819, filed Nov. 27, 1978, discloses a method for preparing an abrasive silicon oxide coating (SiO.sub.x, wherein 1.ltoreq.x.ltoreq.2) on a substrate based on glow discharge deposition from starting materials including silane and a gaseous, oxygen-containing compound selected from the group consisting of N.sub.2 O, H.sub.2 O, and CO.sub.2. These SiO.sub.x coatings are sufficiently abrasive to be employed in the lapping of a diamond playback stylus. However, a more abrasive coating which would decrease lapping time would be desirable.